Princes Parade remediation work

Princes Parade is a former landfill site, meaning remediation work will need to be carried out on the site to ensure it remains a safe environment for all.

Dealing with contaminated sites isn't a new thing - in fact the Millennium Dome (now The O2 Arena) and Olympic Park projects in London show what can be achieved.

Professionally-recognised investigations have helped gain a detailed understanding of the Princes Parade site. It shows a wide range of materials from its previous use are beneath the surface of both the eastern and western portions of the site.

What has been found on the site?

The contents are wide ranging but include - for example - rubber tubing, wood, plastic sacks, crockery, textiles, bottles of bleach and shampoo, asbestos pipes and fragments.

Evidence of contamination in the ground were also found, including elevated levels of petroleum hydrocarbons, heavy metals and Polycyclic aromatic hydrocarbons (PAHs).

A number of remediation methods will be included in our strategy, which has been accepted in principle by the Environment Agency. It will later be subject to statutory body consultation and regulatory approval before any construction work takes place.

All necessary precautions to protect the community and environment from any risks associated with past land contamination will be taken.

Daniel Brenchley, construction manager at BAM Construct, explains:

What is the council doing to keep the public safe now and in the future?

Airborne particles

Those who live and work in the area are understandably concerned about the risk of breathing in materials, such as asbestos, from the former landfill tip.

Six different monitors at various locations on the site are checking for any asbestos fibres released due to ground disturbance.

Air monitoring tests are carried out in accordance with agreed remediation plans when operations on site that disturb the surface area of the site are being carried out. Monitoring is not being carried out when there is no such activity on site.

When operations on site significantly disturb the surface, active air sampling will be carried out on the boundary of the site to monitor for airborne dust and vapours. If threshold levels - still below the HSE occupational health levels where there is a threat to public safety - are exceeded then extra measures will be implemented.

Some excavation work will be required on site - for the installation of the swimming pool, for example - so areas containing such materials will be subject to dampening down prior to and during excavation to prevent particulates becoming airborne.

Covering of materials will be undertaken if they are required to be stockpiled for any duration of time.

Polycyclic aromatic hydrocarbons (PAHs)

PAHs are ubiquitous contaminants.  The levels found at this site are significantly less than the sort of contaminant concentrations seen in - for example - old gasworks, where PAH contamination of 20,000 mg/kg is routinely dealt with.

PAHs come in a very wide range of forms.  They have been much studied over the years and there is a consensus on their toxicology.

The contamination risks at this site are familiar and can be controlled using well-established mitigation procedures in accordance with:

• The law
• Regulations

Best practice guidance (e.g. World Health Organisation, Environment Agency, Health and Safety Executive, UK Health Security Agency)

Phased approach

A phased approach will be taken to the development to control the working zones and enable a systematic approach to working areas. This will reduce the scale of any risk to be mitigated.

Specific equipment and procedures will be used to immediately quarantine and assess any unexpected landfill materials that might be encountered and to mitigate their impact. Resources will be prepared for deployment.

Capping to be placed

This will isolate the site contamination from exposure to the environment and the public. This pathway intervention is a well-used industry technique on brownfield sites which prevents known contaminants from escaping or being accessed.

Other information

Fencing and welfare will be provided to all operatives, as well as wheel washing facilities and the provision of traffic marshals.

The final level of remediation controls and mitigations used specifically on the residential areas of the site will be delivered by the residential developer and their consultant team.

Answering your questions

A number of questions about the planned remediation work were asked by members of the cabinet on 26 January 2022. The main points raised have also been summarised below.

Have you been able to gain a clear picture of the contamination on the Princes Parade site?

Yes - while it would be incredibly difficult to establish and locate every single piece of contamination at this time due to the size of the site, investigation work has allowed us to establish the broad range of materials we can expect to encounter.

Areas where excavation work will be necessary have been subject to more thorough investigation. These detailed assessments have helped shape the strategy to ensure the remediation and construction work is carried out safely and responsibly.

While enough information has been gathered to allow for decisions about the project to be made, further rigorous investigation work will be carried out on the site as is standard practice as the project progresses.

This is to meet safety requirements for workers and the public.

Some people have suggested Princes Parade is one of the most contaminated site in the country. Is that true?

No - this is not the case. In some other sites, outside of the district used by heavy industry, 20 times the amount of contamination seen at Princes Parade has been found.

The main principle of this project is to ensure the site is suitable and safe now and in the future.

What is a clean cover and capping approach and why is it being used on the Princes Parade site?

Once in place a clean cover or capping will prevent unwanted contact with contaminated land beneath.

It is an approach that has been successfully used on a significant number of contaminated sites across the country for decades - and is proven to work. Recent examples include the Millennium Dome (now The O2 Arena) and Olympic Park projects in London.

The clean cover approach is just one of the remediation methods we have in place for the site. Special membranes will stop vapours coming up from the former municipal waste tip into the buildings.

Will taxpayers have to fund the bill if unexpected contamination is found on the site?

No - BAM Construct will take on the financial risk once it is contracted to deliver the second phase of the project (remediation, road and leisure centre construction).

The price to Folkestone & Hythe District Council is fixed. Therefore any such discoveries will have no implication for the taxpayer or the council.

How will you be keeping the public safe while work is carried out?

Air tests are regularly carried out to ensure the safety of the public. Six different monitors at various locations on the site are checking for any asbestos fibres released due to ground disturbance.

Only 1.5 fibres were detected in a recent sample of 2,800 litres of air. This is below the quantification limit and therefore no further action is required.

Effective mitigations such as water suppression are being used on site when materials have to be excavated. If threshold levels are exceeded, then extra measures will be implemented.

Work will be carried out in phases and dedicated work parcels to restrict the amount of materials exposed at any one time.

In terms of materials that have to be excavated, these will be dealt with very locally within the site and will be subject to water suppression and covering to limit the risk to those working and living in the area.

Environmental boundary and activity monitoring will be in place to protect the public and construction workers.

Active air sampling will be carried out on the boundary of the site to monitor for airborne dust and vapours. If threshold levels - still below the HSE occupational health levels where there is a threat to public safety - are exceeded then extra measures will be implemented.

Can you assure me that the work carried out to date has been safe?

No risk to public safety has been brought about by the work carried out to date on the Princes Parade site.

While the top layer of vegetation for the ecology zone has been stripped back this is right on the edge of the landfill site.

No dangerous materials have been encountered by those working on site - only some elements of bricks and masonry, neither of which are of any concern.

Could oil contaminants make their way into the sea?

The drainage is a closed-type system. It includes an oil interceptor meaning any surface water that goes out to sea will not contain any oil.

What about other contaminants from the site?

There is no risk of contaminants from the site accessing the drainage.

The rainfall is being taken from the development via a surface water drainage system out to the sea. No pollutants will make their way through that system as it is a closed type system.

The rainfall lands on the hard landscaping elements (e.g. road or a parking areas) and will go through oil interceptors so that the water will go out to sea clean. At the moment the road run-off goes directly off the road to the beach.

Will contamination be pushed up by the rising water?

No, there tends to be a smear zone created within the range of the tidal movement of the groundwater. This is basically contamination that is clinging to the soil particles.

It's easily distinguishable and not mobile, meaning there is no risk of it being pushed upwards.

The boreholes that have been put in and the water monitoring that's been undertaken haven't found contamination in the groundwater there. There may have been more mobile elements in the past but they are not currently being detected.

Are the pipes being used appropriate for the site? And how will utility companies avoid contaminated land in the future?

Barrier pipes are typically used on contaminated land. This is a standard and well-trusted method and will be implemented at the Princes Parade site.

Gas, electricity, water and telephone infrastructure will be in clean cover service corridors. These are areas filled with assuredly clean materials only. This means anyone digging these areas will not encounter contaminated land in the future.